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Full text of "Insecticides for use in livestock-dipping vats"

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June 1954 E-880 

United States Department of Agriculture 

Agricultural Research Service 

Entomology Research Branch 


Prepared by the Section of Insects Affecting Man and Animals \J 

During the last 5 years millions of cattle, sheep, and goats in the 
southern United States have been treated in dipping vats to control ticks 
and insects. Some ranchers still use the soluble -arsenic dip originally 
introduced for cattle tick control, but the arsenic has largely been 
displaced by modern insecticides. 

The insecticides now most widely used in these vats are toxaphene 
and a mixture of DDT and BHC. Toxaphene wettable powders formulated 
for use in dipping vats have recently become available, and research 
indicates that they can be safely used. The Department has not previously 
recommended emulsion dips of toxaphene or DDT -BHC, because early 
experience showed that they were hazardous. However, during the last 
few years commercial formulations have been greatly improved, and it is 
now possible for cattle to be safely dipped in certain toxaphene emulsions. 

Spraying the insecticides with a power sprayer is still the preferred 
treatment for general use, but since thousands of dipping vats are 
currently being used to treat livestock with toxaphene and DDT -BHC, 
information is presented herein to guide manufacturers who formulate 
insecticides for the dipping-vat market. Instructions for use in the vats 
are also given. 

1_/ J. C. Clark, Rowland Richards, and B. I. Sparr conducted the 
field and laboratory tests under the direction of R. C. Bushland. H. V. 
Claborn, of the Section of Insecticide Investigations, guided the chemical 
studies. R. D. Radeleff, of the Animal Disease and Parasite Branch, 
advised the workers and conducted the basic experiments on toxicity of 
dips to farm animals. 

2 - 

most ping vats have a capacity of 2,000 gallons or more. 

Owner! do not pump them out and clean them 
during a dipping season, but i . add water and insec to compens, 

for en out by th< tock. although fresh dip may be added 

almos' it is used, some of th< inal d :>ains in the 

for about 6 months. 

Before 1950 there were some fatalities among the dip: ock due 

to deterioration of the emulsion on standing. The animals could be saf< 

1 in freshly mixed dip, but as it aged the pai size of the OJ 

phase : ed, leaving a I r deposit on the hair of dipped anin.. 

• al. 5). There is only a small margin of safety be' n the amount 
of insecticid .ired for control of ticks and the amount that is toxic to 

some farm animals (Radeleff and Bushland 3). The deposits fron I i- 

dips exceeded this margin of safety. On this account toxap' us 

not recommended for use in dipping vats until sufficient evident 
•liable that it could be used sa: 

During the reasons of 1951, 1952, and 1953 the performance of commer- 
ily form.. .as closely o 

workers of tl I lie, Tex., laborator\ dips were used fc 

>1 of insects and ticks affecting cattl. and goats. Each til 

: dip samples were taken U i hair 

sampli •■ > i >m cat' rid after dipping and ana for 

Lount of insecticide. Microst ; . i \aminations of dip es to 

>articl< ' also mad< 

To\ I .nulls. ;.-• 

Emu] a • h two commi 

fial i rformed sui i i fully, In additj a- 

■ >n lim ■ 

heir own field expi on th> 

of th< restock o* [t wi 

d formula! luring 

In fresh mixtuj i 




nd of *• 

- 3 - 

appropriate amounts of fresh concentrate and water, the deposits on the 
hair increased 50 percent, to about 1.5 percent of the weight of the hair. 
This is considered the maximum deposit that can be safely tolerated by 
the most susceptible farm animals. These results were observed on the 
very best formulations. Some inferior formulations caused excessive 
deposits after only 2 weeks ' aging. 

Laboratory Evaluation 

It is recognized that the dip manufacturer cannot check his product by 
the elaborate field studies outlined above, but some kind of a laboratory 
procedure is required to check on dip stability. At the Orlando, Fla., 
laboratory Sparr and Bowen (4) worked on emulsion-stability specifications 
in connection with their research to develop insecticides for clothing impreg- 
nation. One of the leading manufacturers of toxaphene emulsifiable concen- 
trates has made intensive laboratory studies of emulsion stability. At 
Kerrville the Orlando procedures have been combined with some of the 
features developed by the industrial cooperator to establish a technique for 
evaluating the emulsion stability of prospective livestock dips. That 
procedure is described below. 

Apparatus . - - The emulsibility tube is a 22-mm. outside diameter Pyrex 
tube (Corning Code No. 234220) 4 feet long, joined to a 15-ml. conical cen- 
trifuge tube (Corning Cat. No. 8080). Although a ground-glass connection 
has been used, a 1-inch length of Tygon tubing of l/2-inch inside diameter 
and 3/32-inch wall thickness makes a satisfactory connection. The mouth 
of the centrifuge tube is fitted flush with the end of the 4-foot tube. Centri- 
fuge tubes graduated in 0.1-ml. divisions are used for accuracy in making 
the sedimentation readings. 

A tipless measuring pipette, prepared by cutting off the tapered tip 
below the 5 -ml. mark and grinding the end to a smooth, flat surface, is 
used for introducing the toxaphene concentrate into the emulsibility tube. 

Test Waters . --Distilled water, a synthetic soft water (Lange j_), and 
a synthetic hard water (Navy Department 2) are used. The type and 
composition of the waters are given below. 

Hardness Composition, grams per liter 

Calcium Sodium Magnesiv 

chloride bicarbonp+e chloride 

Type of water (p p.m. of Calcium Sodium Magnesium 



Distilled None 

Naturally softened 20 0.0094 0.8000 0.0103 

Navy hard 500 .2345 -- .2680 

- 4 - 

st is conducted at 80° -t 5° F. The insectici : 
concentrates and • should be at room temperatu: 

Hold the ernulsibility tube vertically in a rack and f: wi1 t wat< 

to k 2-1/2 inches below its mouth. About 350 ml. is require 

e sufficient concentrate to give a 0.5-percent toxaphene emulsion 
into the tube with the tipless pipette, holding it vertically so that the delivery 
end is in the same plane as and in the center of the mouth of the emulsibi: 
tube. "*ote the rapidity and degree of disintegration of the concentrate, and 
make observations for bottom creaming or breaking of the emulsion af" 
1 hour, 24 hours, and 30 days. 

1 Vrformance Specifications .--The results expected from this evaluation 
-cedure are based on the performance of the two commercial concentrates 
that have proved satisfactory in ranch dipping vats. One of those concen- 

es contains 50 percent of toxaphene, 10 percent of an emulsifying ap- 
(a blend of nonionic and anionic emulsifiers), and 40 percent of a petroleum 
distillate similar to Stoddard's solvent. The other concentrate contains 61 
percent of toxaphene, 12.5 percent of emulsifier (a blend of nonionic and 
anionic surfactants), and 26.5 percent of kerosene. 

The insecticide should disperse spontaneously in all tes* *.-•, rs, with 
oil phase breaking up as it sinks. No oil droplets should r the 

of the tube. After 1 hour's standir,: nould be no mo: in a 

e of bottom cream. After 24 hours 1 standing there should be no mt 
tnan °- '" r bottom cream, and a- should r ■ | complete 

<>n on- | sion of the tube. The tube should be stoi A left to 

At thai tin. oing should not be 

gr< than after the first 24 hours. 

:>ass tl 
" dippin. B t any on. 

•n 50 | of toxaphei 


lOUld | . Th.- I : 

••■■ I 

In b Btabili 

I • 

- 5 - 

Toxaphene Wettable Powders 

Four commercial toxaphene wettable powders, each containing 40 
percent of toxaphene, were studied in field and laboratory tests. They 
were compared with a DDT-BHC wettable powder that is widely sold and 
has been satisfactory for general use. The specifications as given by the 
manufacturers varied considerably. All four toxaphene wettable powders 
gave satisfactory insect control, resuspended normally, and did not cause 
excessive deposits of toxaphene as measured by analyses of hair from 
cattle dipped during the 6 months' season. 

The average particle size should not greatly exceed 7 microns and at 
least 98 percent of the powder should pass a 325-mesh sieve. Fuller's 
earth and other suitable clays are satisfactory diluents. The powder should 
contain adequate amounts of wetting and dispersing agents. 

Laboratory Evaluation 

The following laboratory test of the suitability of a toxaphene wettable 
powder for dipping-vat use is suggested: 

Put 3.2 liters of tap water at room temperature into a 1-gallon glass 
jug. Add wettable powder equivalent to 16 grams of actual toxaphene, 
pouring the dry powder onto the surface of the water. Without agitation 
all the powder should become wet and sink below the surface within 10 
minutes. It should appear well dispersed after seven inversions of the jug. 
Do not shake the jug vigorously but merely turn it upside down seven times. 
The dispersed powder should not flocculate. There should be no appreci- 
able settling during the first 5 minutes after inversion and only about l/2 
inch of sediment after 1 hour. The powder should not cake on standing 
overnight, but should resuspend as easily as it did 1 hour after mixing. 

Use of Insecticides in Dipping Vats 

Toxaphene, whether in an emulsifiable concentrate or a wettable powder, 
should be employed at a concentration of 0.5 percent. DDT in wettable 
powder should also be used at a concentration of 0.5 percent. For control 
of lice and horn flies DDT alone is satisfactory, but if animals are being 
dipped for tick control there should be added enough BHC wettable powder 
to give 0.025 to 0.03 percent of the gamma isomer. Some manufacturers 
supply DDT-BHC powders already mixed in the proper proportions. 

n mil ii ii mi 

3 1262 09240 9258 

lghly clean th€ r tfir>K- Fill it with water to a 

(1 line and then add tl | aired amount of insecticide. Do 

not filacer all the ins< spot. Pour an emulsifiable concentrate 

uniformly along the full length of th< i scat' owder o\ 

surf.' Mix the insecticide thoroug] dragging a 

bui through " 'imes. Dipping should follow 

immediately. Each time the vat is used for subsequent dippings, remix it in 
the same way. When it is necessary to prepare more dip to replace that 

. stock, fill the vat to the dipping line with a measured amount of 
! then add sufficient ins- to compensate for this w 

ts should be cleaned and freshly chai i at the beginning 
f tl eason men th< n continued ust . N 

should b* 1 longer than 6 months without cleaning and recharging. 


th toxa and BHC are toxic to farm animals if appli. xcessive 

amounts. Therefore, all . and inseel Id be carefully rr. d. 

Young animals under 3 months of age and emai particu- 

Ly susceptil cide poison dd so should be dipped with special 

it ion. 

Toxaphene, DDT, or BHC should not be used on ag milk for human 


f from adjacent pastures s- 

A taken! al 

from dipping vats I • nol pollute sir ' 

Literature Cited 

(l) L • Bandbook of Chemistry, p. 780. Handbo 

1 a c . , s ky, Ol 

2) Navy D 16. S: rate 1 

) | : . K. I)., ind El. C. and. 1950. 

m toek. •• 

I ) V. Bow< I i of < . 


(In pn ) 

) B. I.. J. < I -- 105 


i . s.